This relates generally to imaging devices, and more particularly, to imaging devices having low-voltage transistors.
Image sensors are commonly used in electronic devices such as cellular telephones, cameras, and computers to capture images. In a typical arrangement, an electronic device is provided with an array of image pixels arranged in pixel rows and pixel columns. Circuitry is commonly coupled to each pixel column for reading out analog image signals from the image pixels. Power sources (e.g., voltage sources) are used to provide a power supply voltage to image pixels to drive the circuitry.
The driven circuitry may include transistors that form analog circuits and digital circuits. Transistors in the analog circuits coupled directly to the pixel array should therefore be tolerant of high voltages (i.e., should handle the maximum image pixel voltage), thereby requiring transistors with high gate, drain and source voltage tolerances. These transistors cost more die area and have lower scalability because of its need to handle high voltages from 0V to the maximum image pixel voltage, which is not scalable. In mixed-signal applications, using the most advance process technology for digital circuitry is not economical due to analog circuitry limitations.
It would therefore be desirable to be able to provide imaging devices with low-voltage transistors for analog circuits.